Golf ball including a long-chain branched neodymium-catalyzed polybutadiene component

ABSTRACT

The invention is directed to a golf ball comprising a long-chain branched neodymium-catalyzed polybutadiene having a cis-1,4 content of at least about 96% and a solution viscosity of less than 165 mPa·s, wherein the overall golf ball comprises a COR of at least about 0.780 and an Atti compression of from about 25 to about 120. The invention is also directed to a golf ball comprising a core, a cover and optionally an intermediate layer disposed between the core and the cover; wherein at least one of said core, cover and intermediate layer comprises a polybutadiene composition comprising a long-chain branched neodymium-catalyzed polybutadiene having a cis-1,4 content of at least about 96% and a solution viscosity of less than 165 mPa·s. In another embodiment, the golf ball comprises a core, a cover and optionally an intermediate layer disposed between the core and the cover; wherein said core comprises a polybutadiene composition comprising a long-chain branched neodymium-catalyzed polybutadiene having a cis-1,4 content of at least about 96% and a solution viscosity of less than 165 mPa·s.

FIELD OF THE INVENTION

This invention is directed to golf balls and methods for making golfballs incorporating materials which not only create desirable golf ballplaying characteristics such as greater distance due to high COR, butalso have broad application in targeting a wide range of compressionsmeanwhile possessing excellent processability in terms of quality ofmix, extrudability, appearance (surface smoothness of extrudate),controlled cold flow, greater green strength, suitable tack and lessbackrinding, all thereby facilitating and reducing overall golf ballmanufacturing costs.

BACKGROUND OF THE INVENTION

Golf balls are generally classified as either solid or wound. Solid golfballs are typically made with a solid core encased by a cover, both ofwhich can have multiple layers, such as a dual core having a solidcenter and an outer core layer, or a multi-layer cover having an innerand outer cover layer. Additionally, one or more intermediate layers maybe disposed between the core and cover. Golf ball cores and/or centersare conventionally constructed with a thermoset rubber, typically apolybutadiene-based composition, although alternatives such asthermoplastic materials or highly neutral polymers have also beenutilized to date. Wound golf balls, precursors to the solid golf ball,typically include a solid, hollow or fluid-filled center, surrounded bytensioned elastomeric material and a cover.

In this regard, the core is the “engine” of the golf ball when hit witha club head. That is, it is the spring of the ball and its principalsource of resiliency. Meanwhile, the intermediate layers, often based onionomers, aid in maintaining initial speed, contribute to desired spinrate, and improve playability/impact durability as well as acting as amoisture barrier to protect the cores from COR loss. Golf balls havingan overall high COR or coefficient of restitution permit a golfer toachieve desirable travel distance when striking the ball with the club.The cover, while originally intended to protect the golf ball fromscuffing, may also be modified to target a desired spin rate, feel, andplayability, even addressing such issues as “lift” and “drag”.

Accordingly, many golfers prefer a ball having an overall high COR. Thedistance that a golf ball travels upon impact is a function of at leastthe COR and the aerodynamic characteristics of the ball. For golf balls,COR has been approximated as a ratio of the velocity of the golf ballafter impact to the velocity of the golf ball prior to impact, rangingfrom 0 to 1.0. A COR value of 1.0 is equivalent to a perfectly elasticcollision, that is, all the energy is transferred in the collision. ACOR value of 0.0 is equivalent to a perfectly inelastic collision—thatis, all of the energy is lost in the collision. Accordingly, the higherthe golf ball COR, the greater the golf ball travel distance with thesame drive energy upon impact with a golf club.

Meanwhile, many accomplished golfers who are better able to control theball's flight and positioning on the green also prefer a golf ballhaving a softer feel, lower compression and higher spin. Early solidgolf balls lacked the softer feel, lower compression and higher spinrate of wound golf balls. More recently, however, cores of solid golfballs have been heated and crosslinked to create certaincharacteristics, such as higher or lower compression, which affects theball's spin rate off the driver as well as the feel.

Initially, compression was referred to as the tightness of the windingsaround a golf ball. Today, compression refers to how much a ball willdeform under a compressive force when a driver hits the ball. A ballactually tends to flatten out when a driver meets the ball; it deformsout of its round shape and then returns to its round shape, all in asecond or two. The lower the compression rating, the more the ball willcompress or deform upon impact. Atti or PGA compression, a commonmeasure of compression, ranges from about from about 25 to about 120.

Generally, the more deformable the cover is, the easier it is to impartspin to the balls. This is particularly true for short or wedge shots.This may also be accomplished in a hard cover golf ball, for example,where the core is temporarily deformable when the cover is struck by aclub. Meanwhile, altering the composition of an intermediate layer mayalso help to achieve such desired properties.

It is desirable to match golf ball compression rating with a player'sswing speed in maximizing a golfer's performance on the green. Althoughthe compression of a ball alone does not determine whether a ball fliesfarther it can certainly influence or contribute to overall distance.Accordingly, golfers with a slower swing or slower club head speed willdesire a ball having a lower compression rating (softer ball) in orderto prevent losing yardage which would occur if that golfer used a highercompression ball. In turn, golfers with a faster swing or faster clubhead speed will desire a ball having a higher compression rating.

Accordingly, manufacturers seek to develop golf balls incorporatingversatile materials which provide high overall golf ball COR yet may bemodified easily and inexpensively within conventional manufacturingprocesses to target a wide range golf ball compressions of from about 25to about 120 according to each golfer's swing speed without compromisingcontrolled processability.

Controlled processability in golf ball materials remains an importantconsideration as processing difficulties translate to higher overallgolf ball production costs. Here, processing difficulties include bothmaterials handling and manufacturing issues. One handling concern iscold flow, often encountered with bales of uncured rubber during storageand shipment. A solid material X (such as rubber) possesses a propertycalled Cold Flow to the extent that material X permits a second solidmaterial Y to pass through, displace or otherwise permanently change theshape of solid material X over time from the impact of material Y withmaterial X or under pressure applied by material Y toward material X.While temporary deformation or compression of a golf ball as discussedearlier is indeed a desirable golf ball property, cold flow orcreep—permanent deformation of golf ball materials under constantcompressive load—is not. Accordingly, there is a need for an improvedgolf ball comprising materials which provide or contribute to a high CORand a wide range of compressions of from about 25 to about 120 andmanifesting controlled cold flow.

Cold flow is not the only processing hurdle faced by golf ballmanufacturers in producing golf balls having high COR and variedcompression. Low Green strength (the strength of uncured rubber) affectsa composition's ability to withstand milling, sheeting and extruding,for example. Golf ball manufacturers desire materials having sufficientgreen strength to withstand these processes.

Poor extrudability, roughness of the extrudate, inconsistent quality ofmix, insufficient degree of tack and backrinding, are additionalprocessing/handling problems which golf ball manufacturers have faced inmanufacturing golf balls with high COR within a wide range ofcompressions. Regarding tack, a balance must be struck between amaterial having sufficient tack to adhere to another material, yet notpossessing so much tack that it sticks to the mold for example, therebyinterfering with molding operations. Meanwhile, backrinding is anartifact of the molding process, for example, when a compositioncontinues to expand during curing and tears away at mold parting lines.

Previous attempts to incorporate neodymium-catalyzed polybutadienerubbers in high COR golf balls for a broad range of compressions havemet processing difficulties. For example, a high COR golf ball has beendisclosed having a core comprising a blend of up to about 50% of aneodymium-catalyzed polybutadiene rubber such as Bayer's CB-22 (highlylinear) with a cobalt-catalyzed polybutadiene rubber. However, theprocessing ability of the blend was found to decline as the amount ofthe highly linear neodymium-catalyzed polybutadiene in the blend wasincreased and the amount of the cobalt-catalyzed polybutadiene rubberwas correspondingly reduced. See, e.g., U.S. Pat. No. 6,426,387 of Kim,at col 3, lines 59-62.

Other high COR golf balls are disclosed having cores incorporating aneodymium-catalyzed polybutadiene rubber (such as Bayer's/Lanxess CB-23and CB-24 (both linear) in an amount of from about 30% by weight toabout 45% by weight of the core in a blend with cobalt-catalyzedpolybutadiene rubber. There, it was found that processing difficultieswere avoided within those neodymium-catalyzed polybutadiene contentranges. See e.g., U.S. Pat. No. 6,315,684 of Binette et al., col. 9. Asingle neodymium-catalyzed polybutadiene had also been incorporated in agolf ball core in a content range of 55 wt % to 75 wt % of the corewhere the core compression is below 50 and the overall golf ballcompression is 35 to 50 with a high overall golf ball COR of at least0.780. See U.S. Publ. Nos. 2010/0087274 and 2010/0087277 of O G G et al.

Accordingly, there is a need for a high COR golf ball which incorporatesat least one neodymium-catalyzed polybutadiene component whose structureand properties permit its incorporation in a golf ball in a wide wt %content range to achieve a broad spectrum of desired overall golf ballcompressions, meanwhile providing excellent processability. Suchversatility in the polybutadiene component would facilitate golf ballmanufacture as well as reduce golf ball manufacturing/production costs.

SUMMARY OF THE INVENTION

High COR golf balls according to the invention incorporating along-chain branched neodymium-catalyzed polybutadiene component(hereinafter referred to as “LCBNCP”) having a cis-1,4 content of atleast about 96% and a solution viscosity of less than 165 mPa·s possessexcellent golf ball processability and uniformity in product qualityacross a wide range of overall golf ball compressions. The LCBNCP maycomprise at least one of the following: a long-chain branchedneodymium-catalyzed polybutadiene; a long-chain branchedneodymium-catalyzed polybutadiene composition including a long-chainbranched neodymium-catalyzed polybutadiene; and a polybutadienecomposition including the long-chain branched neodymium-catalyzedpolybutadiene. The LCBNCP may also comprise blends of a long-chainbranched neodymium-catalyzed polybutadiene, a long-chain branchedneodymium-catalyzed polybutadiene composition and/or a polybutadienecomposition.

The LCBNCP, having long-chain branches and exhibiting a smaller spacialextension in solution, demonstrates a lower solution viscosity thanother neodymium-catalyzed polybutadiene compositions at a givenmolecular weight, Mooney Viscosity and polydispersity. This facilitatescoordination between and movement among the various polymeric segments,thereby permitting great and controlled processability as well asparticular compatability between the LCBNCP and other golf ballmaterials. Such processing characteristics include excellent quality ofmix, extrudability, extrudate surface smoothness, controlled cold flow,greater green strength, suitable tack and less backrinding. Accordingly,manufacture/production of the golf ball of the invention is easier andless expensive.

A golf ball of the invention may include a long-chain branchedneodymium-catalyzed polybutadiene having a solution viscosity of lessthan 165 mPa·s in a very wide wt % content range of from at least about5 wt % of the golf ball to achieve a broad spectrum of desired overallgolf ball compressions of from about 25 to about 120 without displayingcompromised (uncontrolled or inferior) processability or golf ballproduct quality. The long-chain branched neodymium-catalyzedpolybutadiene may also be incorporated in any or all of the golf ballcore, intermediate layer and cover in an amount of at least about 5 wt%.

In one embodiment, the golf ball comprises at least about 5 wt % of thelong-chain branched neodymium-catalyzed polybutadiene. The golf ball mayalso comprise the long-chain branched neodymium-catalyzed polybutadienein an amount of at least about 10 wt % or at least about 15 wt %.Alternatively, the golf ball may also comprise the long-chain branchedneodymium-catalyzed polybutadiene in an amount of from about 2 wt % toabout 5 wt % or greater.

The golf ball may also comprise a long-chain branchedneodymium-catalyzed polybutadiene composition having a cis-1,4 contentof at least about 96% and a solution viscosity of less than 165 mPa·s.This overall golf ball also comprises a COR of at least about 0.780 anda PGA compression of from about 25 to about 120.

In one embodiment, the golf ball comprises at least about 5 wt % of along-chain branched neodymium-catalyzed polybutadiene composition. Thegolf ball may also comprise the long-chain branched neodymium-catalyzedpolybutadiene composition in an amount of from about 10 wt % to about 85wt % or from about 10 wt % to about 75 wt % or from about 5 wt % toabout 75 wt % or from about 20 wt % to about 75 wt % or from about 15 wt% to about 85 wt % or even from about 15 wt % to about 65 wt % and evenfrom about 10 wt % to about 95 wt %. Alternatively, the golf ball mayalso comprise the long-chain branched neodymium-catalyzed polybutadienecomposition in an amount of from about 75 wt % to about 95 wt % or fromabout 75 wt % to about 85 wt % or from about 55 wt % to about 95 wt %.Meanwhile, the golf ball may also comprise the long-chain branchedneodymium-catalyzed polybutadiene composition in an amount of from about5 wt % to about 95 wt % or from about 5 wt % to about 85 wt % or fromabout 5 wt % to about 55 wt % or from about 5 wt % to about 45 wt % orfrom about 5 wt % to about 35 wt %. Also, the golf ball may alsocomprise the long-chain branched neodymium-catalyzed polybutadienecomposition in an amount of from about 35 wt % to about 95 wt % or fromabout 45 wt % to about 95 wt % or from about 65 wt % to about 95 wt %.

The golf ball of the invention may also comprise a long-chain branchedneodymium-catalyzed polybutadiene composition which comprises along-chain branched neodymium-catalyzed polybutadiene in amounts of fromabout 5 wt % to about 85 wt % or from about 5 wt % to about 75 wt % orfrom about 5 wt % to about 65 wt % or from about 5 wt % to about 55 wt %or from about 5 wt % to about 45 wt % or from about 5 wt % to about 35wt % or from about 1 wt % to about 35 wt % or even up to about 100 wt %.Alternatively, the golf ball of the invention may comprise a long-chainbranched neodymium-catalyzed polybutadiene composition which comprises along-chain branched neodymium-catalyzed polybutadiene in amounts of fromabout 55 wt % to about 100 wt % or from about 55 wt % to about 95 wt %or from about 55 wt % to about 85 wt % or from about 55 wt % to about 75wt %. Meanwhile, the golf ball of the invention may comprise along-chain branched neodymium-catalyzed polybutadiene composition whichcomprises a long-chain branched neodymium-catalyzed polybutadiene inamounts of from about 25 wt % to about 100 wt % or from about 35 wt % toabout 95 wt % or from about 45 wt % to about 95 wt % or from about 75 wt% to about 98 wt %.

The golf ball of the invention may comprise a long-chain branchedneodymium-catalyzed polybutadiene composition consisting essentially ofthe long-chain branched neodymium-catalyzed polybutadiene. In anotherembodiment, the golf ball of the invention may comprise a long-chainbranched neodymium-catalyzed polybutadiene composition consisting of thelong-chain branched neodymium-catalyzed polybutadiene.

In another embodiment, the golf ball may comprise a polybutadienecomposition which comprises at least about 5 wt % of a long-chainbranched neodymium-catalyzed polybutadiene. In yet another embodiment,the golf ball may comprise a polybutadiene composition which comprisesat least about 10 wt % of a long-chain branched neodymium-catalyzedpolybutadiene. In still another embodiment, the golf ball may comprise apolybutadiene composition which comprises at least about 15 wt % of along-chain branched neodymium-catalyzed polybutadiene. Alternatively,the golf ball may comprise a polybutadiene composition which comprises along-chain branched neodymium-catalyzed polybutadiene in an amount offrom about 5 wt % to about 100 wt %. In a different embodiment, the golfball may comprise a polybutadiene composition which comprises along-chain branched neodymium-catalyzed polybutadiene in an amount offrom about 5 wt % to about 95 wt %. The golf ball of the invention mayalso comprise a polybutadiene composition which comprises a long-chainbranched neodymium-catalyzed polybutadiene in amounts of from about 5 wt% to about 85 wt % or from about 5 wt % to about 75 wt % or from about 5wt % to about 65 wt % or from about 5 wt % to about 55 wt % or fromabout 5 wt % to about 45 wt % or from about 5 wt % to about 35 wt % orfrom about 1 wt % to about 35 wt % or even up to about 100 wt %.Alternatively, the golf ball of the invention may comprise apolybutadiene composition which comprises a long-chain branchedneodymium-catalyzed polybutadiene in amounts of from about 55 wt % toabout 100 wt % or from about 55 wt % to about 95 wt % or from about 55wt % to about 85 wt % or from about 55 wt % to about 75 wt %. Meanwhile,the golf ball of the invention may comprise a polybutadiene compositionwhich comprises a long-chain branched neodymium-catalyzed polybutadienein amounts of from about 25 wt % to about 100 wt % or from about 35 wt %to about 95 wt % or from about 45 wt % to about 95 wt % or from about 75wt % to about 98 wt %.

In yet another embodiment, the golf ball of the invention comprises apolybutadiene composition consisting essentially of the long-chainbranched neodymium-catalyzed polybutadiene. In still another embodiment,the polybutadiene composition consists of the long-chain branchedneodymium-catalyzed polybutadiene.

The golf ball of the invention may comprise a core, a cover andoptionally an intermediate layer disposed between the core and the coverwherein at least one of the core, cover and intermediate layer comprisesa long-chain branched neodymium-catalyzed polybutadiene in an amount ofat least 5 wt %. In another embodiment, the at least one of the core,cover and intermediate layer comprises a long-chain branchedneodymium-catalyzed polybutadiene in an amount of at least 10 wt %. Inyet another embodiment, the at least one of the core, cover andintermediate layer comprises a long-chain branched neodymium-catalyzedpolybutadiene in an amount of at least 15 wt %.

The golf ball of the invention may also comprise a core, a cover andoptionally an intermediate layer disposed between the core and the coverwherein at least one of the core, cover and intermediate layer comprisesa long-chain branched neodymium-catalyzed polybutadiene composition inan amount of at least about 5 wt %. The long-chain branchedneodymium-catalyzed polybutadiene composition may meanwhile comprise along-chain branched neodymium-catalyzed polybutadiene in an amount of atleast about 5 wt %. And instead, the long-chain branchedneodymium-catalyzed polybutadiene composition may either consistessentially of or consist of the long-chain branched neodymium-catalyzedpolybutadiene.

In another embodiment, the at least one of the core, cover andintermediate layer consists essentially of the long-chain branchedneodymium-catalyzed polybutadiene composition. In yet anotherembodiment, the at least one of the core, cover and intermediate layerconsists of the long-chain branched neodymium-catalyzed polybutadienecomposition.

Alternatively, a golf ball of the invention may comprise a core, a coverand optionally an intermediate layer disposed between the core and thecover wherein at least one of the core, cover and intermediate layercomprises a polybutadiene composition comprising a long-chain branchedneodymium-catalyzed polybutadiene. In this embodiment, the polybutadienecomposition may be included in the at least one of the core,intermediate layer and cover in an amount of at least about 5 wt %. Inanother embodiment, the at least one of the core, cover and intermediatelayer consists essentially of the polybutadiene composition. In yetanother embodiment, the at least one of the core, cover and intermediatelayer consists of the polybutadiene composition.

The polybutadiene composition may meanwhile include a long-chainbranched neodymium-catalyzed polybutadiene in an amount of from about 5wt %. The polybutadiene composition may even either consist essentiallyof or consist of the long-chain branched neodymium-catalyzedpolybutadiene.

In still another embodiment, at least one of the cover and intermediatelayer comprises the long-chain branched neodymium-catalyzedpolybutadiene in an amount of at least about 2 wt %.

Alternatively, the cover may comprise the long-chain branchedneodymium-catalyzed polybutadiene in an amount of at least about 2 wt %.

The golf ball of the invention may comprise a cover and optionally anintermediate layer disposed between the core and the cover wherein atleast one of the cover and intermediate layer comprises a long-chainbranched neodymium-catalyzed polybutadiene composition. In anotherembodiment, the at least one of the cover and intermediate layerconsists essentially of the long-chain branched neodymium-catalyzedpolybutadiene composition. In yet another embodiment, the at least oneof the cover and intermediate layer consists of the long-chain branchedneodymium-catalyzed polybutadiene composition.

Alternatively, the cover may comprise the long-chain branchedneodymium-catalyzed polybutadiene composition. Or, the cover may consistessentially of the long-chain branched neodymium-catalyzed polybutadienecomposition. In another embodiment, the cover may consist of thelong-chain branched neodymium-catalyzed polybutadiene composition.

In still another embodiment, at least one of the cover and intermediatelayer comprises the polybutadiene composition. At least one of the coverand intermediate layer may also consist essentially of the polybutadienecomposition. Or, the at least one of the cover and intermediate layermay consist of the polybutadiene composition.

Alternatively, the cover may comprise the polybutadiene composition. Or,the cover may consist essentially of the polybutadiene composition. Inanother embodiment, the cover may consist of the polybutadienecomposition.

In one embodiment, at least one of the core, cover and intermediatelayer comprises at least about 5 wt % of the long-chain branchedneodymium-catalyzed polybutadiene. The at least one of the core, coverand intermediate layer may also comprise at least about 2 wt % or atleast about 10 wt % or at least about 15 wt % of the long-chain branchedneodymium-catalyzed polybutadiene.

The at least one of the core, cover and intermediate layer may alsocomprise the long-chain branched neodymium-catalyzed polybutadienecomposition in an amount of from about 10 wt % to about 85 wt % or fromabout 10 wt % to about 75 wt % or from about 5 wt % to about 75 wt % orfrom about 20 wt % to about 75 wt % or from about 15 wt % to about 85 wt% or even from about 15 wt % to about 65 wt % and even from about 10 wt% to about 95 wt %. Alternatively, the at least one of the core, coverand intermediate layer may also comprise the long-chain branchedneodymium-catalyzed polybutadiene composition in an amount of from about75 wt % to about 95 wt % or from about 75 wt % to about 85 wt % or fromabout 55 wt % to about 95 wt %. Meanwhile, the at least one of the core,cover and intermediate layer may also comprise the long-chain branchedneodymium-catalyzed polybutadiene composition in an amount of from about5 wt % to about 95 wt % or from about 5 wt % to about 85 wt % or fromabout 5 wt % to about 55 wt % or from about 5 wt % to about 45 wt % orfrom about 5 wt % to about 35 wt %. Also, the at least one of the core,cover and intermediate layer may also comprise the long-chain branchedneodymium-catalyzed polybutadiene composition in an amount of from about35 wt % to about 95 wt % or from about 45 wt % to about 95 wt % or fromabout 65 wt % to about 95 wt %.

The at least one of the core, cover and intermediate layer may alsocomprise a long-chain branched neodymium-catalyzed polybutadienecomposition which comprises a long-chain branched neodymium-catalyzedpolybutadiene in amounts of from about 5 wt % to about 85 wt % or fromabout 5 wt % to about 75 wt % or from about 5 wt % to about 65 wt % orfrom about 5 wt % to about 55 wt % or from about 5 wt % to about 45 wt %or from about 5 wt % to about 35 wt % or from about 1 wt % to about 35wt % or even from about 1 wt % to about 95 wt % or even up to about 100wt %. Alternatively, the golf ball of the invention may comprise along-chain branched neodymium-catalyzed polybutadiene composition whichcomprises a long-chain branched neodymium-catalyzed polybutadiene inamounts of from about 55 wt % to about 100 wt % or from about 55 wt % toabout 95 wt % or from about 55 wt % to about 85 wt % or from about 55 wt% to about 75 wt %. Meanwhile, the golf ball of the invention maycomprise a long-chain branched neodymium-catalyzed polybutadienecomposition which comprises a long-chain branched neodymium-catalyzedpolybutadiene in amounts of from about 25 wt % to about 100 wt % or fromabout 35 wt % to about 95 wt % or from about 45 wt % to about 95 wt % orfrom about 75 wt % to about 98 wt %.

In another embodiment, the at least one of the core, cover andintermediate layer may comprise a polybutadiene composition whichcomprises at least about 5 wt % of a long-chain branchedneodymium-catalyzed polybutadiene. In yet another embodiment, the atleast one of the core, cover and intermediate layer may comprise apolybutadiene composition which comprises at least about 10 wt % of along-chain branched neodymium-catalyzed polybutadiene. In still anotherembodiment, the at least one of the core, cover and intermediate layermay comprise a polybutadiene composition which comprises at least about15 wt % of a long-chain branched neodymium-catalyzed polybutadiene.Alternatively, the at least one of the core, cover and intermediatelayer may comprise a polybutadiene composition which comprises along-chain branched neodymium-catalyzed polybutadiene in an amount offrom about 5 wt % to about 100 wt %. In a different embodiment, the atleast one of the core, cover and intermediate layer may comprise apolybutadiene composition which comprises a long-chain branchedneodymium-catalyzed polybutadiene in an amount of from about 5 wt % toabout 95 wt %. The at least one of the core, cover and intermediatelayer of the invention may also comprise a polybutadiene compositionwhich comprises a long-chain branched neodymium-catalyzed polybutadienein amounts of from about 5 wt % to about 85 wt % or from about 5 wt % toabout 75 wt % or from about 5 wt % to about 65 wt % or from about 5 wt %to about 55 wt % or from about 5 wt % to about 45 wt % or from about 5wt % to about 35 wt % or from about 1 wt % to about 35 wt % or fromabout 1 wt % to about 95 wt % or even up to about 100 wt %.Alternatively, the at least one of the core, cover and intermediatelayer may comprise a polybutadiene composition which comprises along-chain branched neodymium-catalyzed polybutadiene in amounts of fromabout 55 wt % to about 100 wt % or from about 55 wt % to about 95 wt %or from about 55 wt % to about 85 wt % or from about 55 wt % to about 75wt %. Meanwhile, the at least one of the core, cover and intermediatelayer may comprise a polybutadiene composition which comprises along-chain branched neodymium-catalyzed polybutadiene in amounts of fromabout 25 wt % to about 100 wt % or from about 35 wt % to about 95 wt %or from about 45 wt % to about 95 wt % or from about 75 wt % to about 98wt %.

In one embodiment, the long-chain branched neodymium-catalyzedpolybutadiene has a solution viscosity of less than 155 mPa·s. Inanother embodiment, the long-chain branched neodymium-catalyzedpolybutadiene has a solution viscosity of less than 145 mPa·s. In yetanother embodiment, the long-chain branched neodymium-catalyzedpolybutadiene has a solution viscosity of less than 135 mPa·s. In stillanother embodiment, the long-chain branched neodymium-catalyzedpolybutadiene has a solution viscosity of less than 125 mPa·s.Alternatively, the long-chain branched neodymium-catalyzed polybutadienehas a solution viscosity of less than 115 mPa·s. In a differentembodiment, the long-chain branched neodymium-catalyzed polybutadienehas a solution viscosity of less than 105 mPa·s. In still a differentembodiment, the long-chain branched neodymium-catalyzed polybutadienemay have a solution viscosity of less than 95 mPa·s. The long-chainbranched neodymium-catalyzed polybutadiene may also have a solutionviscosity of less than 80 mPa·s or even 70 mPa·s.

In one embodiment, the long-chain branched neodymium-catalyzedpolybutadiene composition has a solution viscosity of less than 155mPa·s. In another embodiment, the long-chain branchedneodymium-catalyzed polybutadiene composition has a solution viscosityof less than 145 mPa·s. In yet another embodiment, the long-chainbranched neodymium-catalyzed polybutadiene composition has a solutionviscosity of less than 135 mPa·s. In still another embodiment, thelong-chain branched neodymium-catalyzed polybutadiene composition has asolution viscosity of less than 125 mPa·s. Alternatively, the long-chainbranched neodymium-catalyzed polybutadiene composition has a solutionviscosity of less than 115 mPa·s. In a different embodiment, thelong-chain branched neodymium-catalyzed polybutadiene composition has asolution viscosity of less than 105 mPa·s. In still a differentembodiment, the long-chain branched neodymium-catalyzed polybutadienecomposition may have a solution viscosity of less than 95 mPa·s. Thelong-chain branched neodymium-catalyzed polybutadiene composition mayalso have a solution viscosity of less than 80 mPa·s or even 70 mPa·s.

In one embodiment, the polybutadiene composition has a solutionviscosity of less than 155 mPa·s. In another embodiment, thepolybutadiene composition has a solution viscosity of less than 145mPa·s. In yet another embodiment, the polybutadiene composition has asolution viscosity of less than 135 mPa·s. In still another embodiment,the polybutadiene composition has a solution viscosity of less than 125mPa·s. Alternatively, the polybutadiene composition has a solutionviscosity of less than 115 mPa·s. In a different embodiment, thepolybutadiene composition has a solution viscosity of less than 105mPa·s. In still a different embodiment, the polybutadiene compositionmay have a solution viscosity of less than 95 mPa·s. The polybutadienecomposition may also have a solution viscosity of less than 80 mPa·s oreven 70 mPa·s.

In one embodiment, in any golf ball of the invention incorporating anLCBNCP having a cis-1,4 content of at least about 96% and a solutionviscosity of less than 165 mPa·s, the appearance (surface smoothness ofextrudate incorporating same), may be improved by up to about 75% overthe appearance of extrudate including neodymium-catalyzed polybutadienecomponents having a solution viscosity of 165 mPa·s or greater.

In another embodiment, in any golf ball of the invention incorporatingan LCBNCP having a cis-1,4 content of at least about 96% and a solutionviscosity of less than 165 mPa·s, the cold flow may be reduced by up toabout 40% over the cold flow of neodymium-catalyzed polybutadienecontaining golf ball components having a solution viscosity of 165 mPa·sor greater.

In yet another embodiment, in any golf ball of the inventionincorporating an LCBNCP having a cis-1,4 content of at least about 96%and a solution viscosity of less than 165 mPa·s, the green strength maybe improved by up to about 50% over that of golf balls includingneodymium-catalyzed polybutadiene containing golf ball components havinga solution viscosity of 165 mPa·s or greater.

In still another embodiment, in any golf ball of the inventionincorporating an LCBNCP having a cis-1,4 content of at least about 96%and a solution viscosity of less than 165 mPa·s, the tack may be up to65% more suitable than that of neodymium-catalyzed polybutadienecontaining golf ball components having a solution viscosity of 165 mPa·sor greater.

Meanwhile, in any golf ball of the invention incorporating an LCBNCPhaving a cis-1,4 content of at least about 96% and a solution viscosityof less than 165 mPa·s, backrinding may be reduced by up to about 50%over neodymium-catalyzed polybutadiene containing golf ball componentshaving a solution viscosity of 165 mPa·s or greater.

In one embodiment, the overall golf ball has a compression of from about25 to about 110. In another embodiment, the overall golf ball has acompression of from about 35 to about 100. In yet another embodiment,the overall golf ball has a compression of from about 45 to about 95. Instill another embodiment, the compression may be from about 55 to about85, or from about 65 to about 75. Meanwhile, the compression may also befrom about 50 to about 110, or from about 60 to about 100, or from about70 to about 90, or even from about 80 to about 110

Generally, in golf balls of the invention, the overall golf ball COR isat least about 0.780. In another embodiment, the overall golf ball CORis at least about 0.788. In yet another embodiment, the overall golfball COR is at least about 0.791. In still another embodiment, theoverall golf ball COR is at least about 0.794. Also, the overall golfball COR may be at least about 0.797. The overall golf ball COR may evenbe at least about 0.800, or at least about 0.803, or at least about0.812.

Another aspect of the invention relates to a method of making a golfball having a COR of at least about 0.780 comprising the steps of:selecting a long-chain branched neodymium-catalyzed polybutadiene havinga cis-1,4 content of at least about 96% and a solution viscosity of lessthan 165 mPa·s; and providing a core, a cover and optionally anintermediate layer disposed between the core and the cover wherein atleast one of said core, cover and intermediate layer is formed from thelong-chain branched neodymium-catalyzed polybutadiene. In anotherembodiment, at least one of said cover and intermediate layer is formedfrom the long-chain branched neodymium-catalyzed polybutadiene. In yetanother embodiment, said cover is formed from the long-chain branchedneodymium-catalyzed polybutadiene.

In each embodiment, the long-chain branched neodymium-catalyzedpolybutadiene may be selected and/or provided in any or all of the core,cover and intermediate layer in any amount as discussed herein. Forexample, the long-chain branched neodymium-catalyzed polybutadiene maybe selected and/or provided in an amount of at least about 2 wt % of anyor all of the core, cover and intermediate layer.

Alternatively, the invention relates to a method of making a golf ballhaving a COR of at least about 0.780 comprising the steps of: selectinga long-chain branched neodymium-catalyzed polybutadiene compositionhaving a cis-1,4 content of at least about 96% and a solution viscosityof less than 165 mPa·s; and providing a core, a cover and optionally anintermediate layer disposed between the core and the cover wherein atleast one of said core, cover and intermediate layer is formed from thelong-chain branched neodymium-catalyzed polybutadiene composition. Inanother embodiment, at least one of said cover and intermediate layer isformed from the long-chain branched neodymium-catalyzed polybutadienecomposition. In yet another embodiment, said cover is formed from thelong-chain branched neodymium-catalyzed polybutadiene composition.

In each embodiment, the long-chain branched neodymium-catalyzedpolybutadiene composition may be selected and/or provided in any or allof the core, cover and intermediate layer in any amount as discussedherein. For example, the long-chain branched neodymium-catalyzedpolybutadiene composition may be selected and/or provided in an amountof at least about 5 wt % of any or all of the core, cover andintermediate layer. In another embodiment, the long-chain branchedneodymium-catalyzed polybutadiene composition may comprise a long-chainbranched neodymium-catalyzed polybutadiene in an amount of at leastabout 5 wt % of the composition. Any or all of the core, intermediatelayer and cover may comprise, consist essentially of or consist of thelong-chain branched neodymium-catalyzed polybutadiene composition.

The invention also relates to a method of making a golf ball having aCOR of at least about 0.780 and a compression of from about 25 to about120. In one embodiment, the method is for controlling the processabilityof the golf ball as defined herein. In particular, the method of makingthe golf ball comprises the steps of: selecting a polybutadienecomposition comprising a long-chain branched neodymium-catalyzedpolybutadiene having a cis-1,4 content of at least about 96% by weightand a solution viscosity of less than 165 mPa·s; and providing a core, acover and optionally an intermediate layer disposed between the core andthe cover wherein at least one of said core, cover and intermediatelayer is formed from the polybutadiene composition. In anotherembodiment, at least one of the intermediate layer and cover comprisethe polybutadiene composition. In still another embodiment, the covercomprises the polybutadiene composition.

In each embodiment, the polybutadiene composition may be selected and/orprovided in any or all of the core, cover and intermediate layer in anyamount as discussed herein. For example, the polybutadiene compositionmay be selected and/or provided in an amount of at least about 5 wt % ofany or all of the core, cover and intermediate layer. In anotherembodiment, the long-chain branched neodymium-catalyzed polybutadienemay be present in the polybutadiene composition in an amount of at leastabout 5 wt %. Any or all of the core, intermediate layer and cover maycomprise, consist essentially of or consist of the polybutadienecomposition.

The LCBNCP may also comprise combinations/blends of a long-chainbranched neodymium-catalyzed polybutadiene, a long-chain branchedneodymium-catalyzed polybutadiene composition and/or a polybutadienecomposition. In a non-limiting example, each is present in the LCBNCP ina ratio of 1:1:1, respectively. In another embodiment, each is presentin the LCBNCP in a ratio of 2:1:1, respectively. In yet anotherembodiment, each may be present in the LCBNCP in a ratio of 4:1:1. Instill another embodiment, each may be present in the LCBNCP in a ratioof 4:2:1. Or, for example, the LCBNCP may include a long-chain branchedneodymium-catalyzed polybutadiene composition and a polybutadienecomposition in a 1:3 ratio. These combinations/ratios are intended asexamples of some of the many other possible combinations/blends/ratiosof an inventive golf ball incorporating an LCBNCP including thelong-chain branched neodymium-catalyzed polybutadiene, long-chainbranched neodymium-catalyzed polybutadiene composition and/orpolybutadiene composition.

DETAILED DESCRIPTION OF THE INVENTION

The cores in the golf balls of this invention may be solid, semi-solid,hollow, fluid-filled, or powder-filled. Typically, the cores are solidand made from rubber compositions containing at least a base rubber,free-radical initiator agent, cross-linking co-agent, and fillers. Inthe golf ball of the invention, the base rubber may be the LCBNCP ofeither: at least about 5 wt % of a polybutadiene composition comprising,consisting essentially of or consisting of a long-chain branchedneodymium-catalyzed polybutadiene; or a long-chain branchedneodymium-catalyzed polybutadiene composition comprising at least 5 wt %of a long-chain branched neodymium-catalyzed polybutadiene. The additionof an LCBNCP in the golf ball provides a golf ball having a high COR andwide range of possible compressions with excellent processabilityrelating to both golf ball materials handling and golf ball manufacture.

One example of a suitable base rubber LCBNCP for the golf ball of theinvention and method of making same is LANXESS BUNA CB 25 (“CB25”).LANXESS' CB 25 is a long-chain branched neodymium-catalyzedpolybutadiene having a solution viscosity of 145, much lower than thesolution viscosities of other LANXESS neodymium-catalyzed polybutadienessuch as CB 22, CB 23, and CB 24. Two neodymium-catalyzed polybutadienesmay have identical Mooney viscosities yet have very different solutionviscosities. For example, while CB 24 and CB 25 both have Mooney's of44, CB 24's solution viscosity is at least 20 mPa·s greater than that ofCB 25. The golf ball of the invention possesses superior processabilityand performance due to the lower solution viscosity of the long chainbranched neodymium-catalyzed polybutadiene at a given molecular weight,Mooney viscosity and polydispersity.

Examples of polybutadiene rubbers for blending with the base rubber mayinclude BUNA® CB22, BUNA® CB23 and BUNA® CB24, TAKTENE® 1203G1, 220,221, and PETROFLEX® BRNd-40, commercially available from LANXESSCorporation; BR-1220 available from BST Elastomers Co. LTD; UBEPOL® 360Land UBEPOL® 150L and UBEPOL-BR rubbers, commercially available from UBEIndustries, Ltd. of Tokyo, Japan; KINEX® 7245 and KINEX® 7265,commercially available from Goodyear of Akron, Ohio; SE BR-1220,commercially available from Dow Chemical Company; Europrene® NEOCIS® BR40 and BR 60, commercially available from Polimeri Europa; and BR 01, BR730, BR 735, BR 11, and BR 51, commercially available from JapanSynthetic Rubber Co., Ltd; and KARBOCHEM® ND40, ND45, and ND60,commercially available from Karbochem.

The base rubber may further include polyisoprene rubber, natural rubber,ethylene-propylene rubber, ethylene-propylene diene rubber,styrene-butadiene rubber, and combinations of two or more thereof.Another preferred base rubber is polybutadiene optionally mixed with oneor more elastomers such as polyisoprene rubber, natural rubber, ethylenepropylene rubber, ethylene propylene diene rubber, styrene-butadienerubber, polystyrene elastomers, polyethylene elastomers, polyurethaneelastomers, polyurea elastomers, acrylate rubbers, polyoctenamers,metallocene-catalyzed elastomers, and plastomers. As discussed furtherbelow, highly neutralized acid copolymers (HNPs), as known in the art,also can be used to form the core layer as part of the blend. Suchcompositions will provide increased flexural modulus and toughnessthereby improving the golf ball's performance including its impactdurability.

The base rubber typically is mixed with at least one reactivecross-linking co-agent to enhance the hardness of the rubbercomposition. Suitable co-agents include, but are not limited to,unsaturated carboxylic acids and unsaturated vinyl compounds. Apreferred unsaturated vinyl compound is trimethylolpropanetrimethacrylate. The rubber composition is cured using a conventionalcuring process. Suitable curing processes include, for example, peroxidecuring, sulfur curing, high-energy radiation, and combinations thereof.In one embodiment, the base rubber is peroxide cured. Organic peroxidessuitable as free-radical initiators include, for example, dicumylperoxide; n-butyl-4,4-di(t-butylperoxy) valerate;1,1-di(t-butylperoxy)3,3,5-trimethylcyclohexane;2,5-dimethyl-2,5-di(t-butylperoxy) hexane; di-t-butyl peroxide;di-t-amyl peroxide; t-butyl peroxide; t-butyl cumyl peroxide;2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3;di(2-t-butyl-peroxyisopropyl)benzene; dilauroyl peroxide; dibenzoylperoxide; t-butyl hydroperoxide; and combinations thereof. Cross-linkingagents are used to cross-link at least a portion of the polymer chainsin the composition. Suitable cross-linking agents include, for example,metal salts of unsaturated carboxylic acids having from 3 to 8 carbonatoms; unsaturated vinyl compounds and polyfunctional monomers (forexample, trimethylolpropane trimethacrylate); phenylene bismaleimide;and combinations thereof. In a particular embodiment, the cross-linkingagent is selected from zinc salts of acrylates, diacrylates,methacrylates, and dimethacrylates. In another particular embodiment,the cross-linking agent is zinc diacrylate (“ZDA”). Commerciallyavailable zinc diacrylates include those selected from RocklandReact-Rite and Sartomer.

The LCBNCP may also comprise low, medium or high Mooney viscosityrubber, or blends thereof. The measurement of Mooney viscosity isdefined according to ASTM D-1646. The Mooney viscosity range ispreferably greater than about 30, as long as the solution viscosity ofthe LCBNCP is less than 165 mPa·s or as otherwise disclosed herein inalternative embodiments.

In one embodiment of the present invention, golf ball cores made withmid- to high-Mooney viscosity polybutadiene material exhibit increasedresiliency (and, therefore, distance) without increasing the hardness ofthe ball.

If desired, the LCBNCP can also be mixed with other elastomers known inthe art, such as other polybutadiene rubbers, natural rubber, styrenebutadiene rubber, and/or isoprene rubber in order to further modify theproperties of the core. When a mixture of elastomers is used, theamounts of other constituents in the core composition are typicallybased on 100 parts by weight of the total elastomer mixture.

Thermoplastic elastomers (TPE) may also be used to modify the propertiesof the core layers, or the uncured core layer stock by blending with thebase thermoset rubber. These TPEs include natural or synthetic balata,or high trans-polyisoprene, high trans-polybutadiene, or any styrenicblock copolymer, such as styrene ethylene butadiene styrene,styrene-isoprene-styrene, etc., a metallocene or other single-sitecatalyzed polyolefin such as ethylene-octene, or ethylene-butene, orthermoplastic polyurethanes (TPU), including copolymers, e.g. withsilicone. Other suitable TPEs for blending with the thermoset rubbers ofthe present invention include PEBAX®, which is believed to comprisepolyether amide copolymers, HYTREL®, which is believed to comprisepolyether ester copolymers, thermoplastic urethane, and KRATON®, whichis believed to comprise styrenic block copolymers elastomers. Any of theTPEs or TPUs above may also contain functionality suitable for grafting,including maleic acid or maleic anhydride. Any of the ThermoplasticVulcanized Rubbers (TPV) such as Santoprene® or Vibram® or ETPV® can beused along with a present invention. In one embodiment, the TPV has athermoplastic as a continuous phase and a cross-linked rubberparticulate as a dispersed (or discontinuous) phase. In anotherembodiment, the TPV has a cross-linked phase as a continuous phase and athermoplastic as a dispersed (or discontinuous) phase to provide reducedloss in elasticity in order to improve the resiliency of the golf ball.

The rubber compositions also may contain “soft and fast” agents such asa halogenated organosulfur, organic disulfide, or inorganic disulfidecompounds. Particularly suitable halogenated organosulfur compoundsinclude, but are not limited to, halogenated thiophenols. Preferredorganic sulfur compounds include, but not limited to,pentachlorothiophenol (“PCTP”) and a salt of PCTP. A preferred salt ofPCTP is ZnPCTP. A suitable PCTP is sold by the Struktol Company (Stow,Ohio) under the tradename, A95. ZnPCTP is commercially available fromEchinaChem (San Francisco, Calif.). These compounds also may function ascis-to-trans catalysts to convert some cis-1,4 bonds in thepolybutadiene to trans-1,4 bonds. Antioxidants also may be added to therubber compositions to prevent the breakdown of the elastomers. Otheringredients such as accelerators (for example, tetra methylthiuram),processing aids, dyes and pigments, wetting agents, surfactants,plasticizers, as well as other additives known in the art may be addedto the rubber composition.

The core may be formed by mixing and forming the rubber compositionusing conventional techniques. These cores can be used to make finishedgolf balls by surrounding the core with outer core layer(s),intermediate layer(s), and/or cover materials as discussed furtherbelow. In another embodiment, the cores can be formed using highlyneutralized polymer (HNP) compositions as disclosed in U.S. Pat. Nos.6,756,436, 7,030,192, 7,402,629, and 7,517,289. The cores from thehighly neutralized polymer compositions can be further cross-linkedusing any free-radical initiation sources including radiation sourcessuch as gamma or electron beam as well as chemical sources such asperoxides and the like.

Golf balls made in accordance with this invention can be of any size,although the USGA requires that golf balls used in competition have adiameter of at least 1.68 inches and a weight of no greater than 1.62ounces. For play outside of USGA competition, the golf balls can havesmaller diameters and be heavier.

The outer core, intermediate layer, inner cover, and/or outer cover mayalso comprise, consist essentially of or consist of the LCBNCP. In someinstances, a traditional thermoplastic or thermosetting composition maybe used to make one layer and the LCBNCP may be used to make a differentlayer of the golf ball depending upon the desired ball constructionplaying performance properties. If a conventional thermoplastic orthermosetting composition is used in one layer (and the LCBNCP used in adifferent layer), then a wide variety of thermoplastic or thermosettingmaterials can be employed. These materials include for example,olefin-based copolymer ionomer resins (for example, Surlyn® ionomerresins and DuPont® HPF 1000 and HPF 2000, commercially available from E.I. du Pont de Nemours and Company; Iotek® ionomers, commerciallyavailable from ExxonMobil Chemical Company; Amplify® 10 ionomers ofethylene acrylic acid copolymers, commercially available from The DowChemical Company; and Clarix® ionomer resins, commercially availablefrom A. Schulman Inc.); polyurethanes; polyureas; copolymers and hybridsof polyurethane and polyurea; polyethylene, including, for example, lowdensity polyethylene, linear low density polyethylene, and high densitypolyethylene; polypropylene; rubber-toughened olefin polymers; acidcopolymers, for example, poly(meth)acrylic acid, which do not becomepart of an ionomeric copolymer; plastomers; flexomers;styrene/butadiene/styrene block copolymers;styrene/ethylene-butylene/styrene block copolymers; dynamicallyvulcanized elastomers; copolymers of ethylene and vinyl acetates;copolymers of ethylene and methyl acrylates; polyvinyl chloride resins;polyamides, poly(amide-ester) elastomers, and graft copolymers ofionomer and polyamide including, for example, Pebax® thermoplasticpolyether block amides, commercially available from Arkema Inc;cross-linked trans-polyisoprene and blends thereof; polyester-basedthermoplastic elastomers, such as Hytrel®, commercially available fromE. I. du Pont de Nemours and Company; polyurethane-based thermoplasticelastomers, such as Elastollan®, commercially available from BASF;synthetic or natural vulcanized rubber; and combinations thereof.

While the inventive golf ball may be formed from a variety of differingand conventional materials for the intermediate layer(s), inner coverlayer(s) and/or outer cover layer(s), preferred cover materials include,but are not limited to:

(1) Polyurethanes, such as those prepared from polyols or polyamines anddiisocyanates or polyisocyanates and/or their prepolymers, and thosedisclosed in U.S. Pat. Nos. 5,334,673 and 6,506,851;

(2) Polyureas, such as those disclosed in U.S. Pat. Nos. 5,484,870 and6,835,794; and

(3) Polyurethane-urea hybrids, blends or copolymers comprising urethaneor urea segments.

Suitable polyurethane compositions comprise a reaction product of atleast one polyisocyanate and at least one curing agent. The curing agentcan include, for example, one or more polyamines, one or more polyols,or a combination thereof. The polyisocyanate can be combined with one ormore polyols to form a prepolymer, which is then combined with the atleast one curing agent. Thus, the polyols described herein are suitablefor use in one or both components of the polyurethane material, i.e., aspart of a prepolymer and in the curing agent. Suitable polyurethanes aredescribed in U.S. Patent Application Publication No. 2005/0176523, whichis incorporated by reference in its entirety.

Any polyisocyanate available to one of ordinary skill in the art issuitable for use according to the invention. Exemplary polyisocyanatesinclude, but are not limited to, 4,4′-diphenylmethane diisocyanate(MDI); polymeric MDI; carbodiimide-modified liquid MDI;4,4′-dicyclohexylmethane diisocyanate (H₁₂MDI); p-phenylene diisocyanate(PPDI); m-phenylene diisocyanate (MPDI); toluene diisocyanate (TDI);3,3′-dimethyl-4,4′-biphenylene diisocyanate; isophoronediisocyanate;1,6-hexamethylene diisocyanate (HDI); naphthalene diisocyanate; xylenediisocyanate; p-tetramethylxylene diisocyanate; m-tetramethylxylenediisocyanate; ethylene diisocyanate; propylene-1,2-diisocyanate;tetramethylene-1,4-diisocyanate; cyclohexyl diisocyanate;dodecane-1,12-diisocyanate; cyclobutane-1,3-diisocyanate;cyclohexane-1,3-diisocyanate; cyclohexane-1,4-diisocyanate;1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane; methylcyclohexylene diisocyanate; triisocyanate of HDI; triisocyanate of2,4,4-trimethyl-1,6-hexane diisocyanate; tetracene diisocyanate;napthalene diisocyanate; anthracene diisocyanate; isocyanurate oftoluene diisocyanate; uretdione of hexamethylene diisocyanate; andmixtures thereof. Polyisocyanates are known to those of ordinary skillin the art as having more than one isocyanate group, e.g.,di-isocyanate, tri-isocyanate, and tetra-isocyanate. Preferably, thepolyisocyanate includes MDI, PPDI, TDI, or a mixture thereof, and morepreferably, the polyisocyanate includes MDI. It should be understoodthat, as used herein, the term MDI includes 4,4′-diphenylmethanediisocyanate, polymeric MDI, carbodiimide-modified liquid MDI, andmixtures thereof. Additionally, the prepolymers synthesized from thesediisocyanates may be “low free monomer,” understood by one of ordinaryskill in the art to have lower levels of “free” isocyanate monomers,typically less than about 0.1% free isocyanate. Examples of “low freemonomer” prepolymers include, but are not limited to Low Free MonomerMDI prepolymers, Low Free Monomer TDI prepolymers, and Low Free MonomerPPDI prepolymers.

Any polyol available to one of ordinary skill in the art is suitable foruse according to the invention. Exemplary polyols include, but are notlimited to, polyether polyols, hydroxy-terminated polybutadiene(including partially/fully hydrogenated derivatives), polyester polyols,polycaprolactone polyols, and polycarbonate polyols. In one preferredembodiment, the polyol includes polyether polyol. Examples include, butare not limited to, polytetramethylene ether glycol (PTMEG),polyethylene propylene glycol, polyoxypropylene glycol, and mixturesthereof. The hydrocarbon chain can have saturated or unsaturated bondsand substituted or unsubstituted aromatic and cyclic groups. Preferably,the polyol of the present invention includes PTMEG.

In another embodiment, polyester polyols are included in thepolyurethane material. Suitable polyester polyols include, but are notlimited to, polyethylene adipate glycol; polybutylene adipate glycol;polyethylene propylene adipate glycol; o-phthalate-1,6-hexanediol;poly(hexamethylene adipate) glycol; and mixtures thereof. Thehydrocarbon chain can have saturated or unsaturated bonds, orsubstituted or unsubstituted aromatic and cyclic groups.

In another embodiment, polycaprolactone polyols are included in thematerials of the invention. Suitable polycaprolactone polyols include,but are not limited to, 1,6-hexanediol-initiated polycaprolactone,diethylene glycol initiated polycaprolactone, trimethylol propaneinitiated polycaprolactone, neopentyl glycol initiated polycaprolactone,1,4-butanediol-initiated polycaprolactone, and mixtures thereof. Thehydrocarbon chain can have saturated or unsaturated bonds, orsubstituted or unsubstituted aromatic and cyclic groups.

In yet another embodiment, polycarbonate polyols are included in thepolyurethane material of the invention. Suitable polycarbonates include,but are not limited to, polyphthalate carbonate and poly(hexamethylenecarbonate) glycol. The hydrocarbon chain can have saturated orunsaturated bonds, or substituted or unsubstituted aromatic and cyclicgroups. In one embodiment, the molecular weight of the polyol is fromabout 200 to about 4000.

Polyamine curatives are also suitable for use in the polyurethanecomposition of the invention and have been found to improve cut, shear,and impact resistance of the resultant balls. Preferred polyaminecuratives include, but are not limited to,3,5-dimethylthio-2,4-toluenediamine and isomers thereof;3,5-diethyltoluene-2,4-diamine and isomers thereof, such as3,5-diethyltoluene-2,6-diamine;4,4′-bis-(sec-butylamino)-diphenylmethane;1,4-bis-(sec-butylamino)-benzene, 4,4′-methylene-bis-(2-chloroaniline);4,4′-methylene-bis-(3-chloro-2,6-diethylaniline);polytetramethyleneoxide-di-p-aminobenzoate; N,N′-dialkyldiamino diphenylmethane; p,p′-methylene dianiline; m-phenylenediamine;4,4′-methylene-bis-(2-chloroaniline);4,4′-methylene-bis-(2,6-diethylaniline);4,4′-methylene-bis-(2,3-dichloroaniline);4,4′-diamino-3,3′-diethyl-5,5′-dimethyl diphenylmethane;2,2′,3,3′-tetrachloro diamino diphenylmethane; trimethylene glycoldi-p-aminobenzoate; and mixtures thereof. Preferably, the curing agentof the present invention includes 3,5-dimethylthio-2,4-toluenediamineand isomers thereof, such as ETHACURE® 300, commercially available fromAlbermarle Corporation of Baton Rouge, La. Suitable polyamine curatives,which include both primary and secondary amines, preferably havemolecular weights ranging from about 64 to about 2000.

At least one of a diol, triol, tetraol, or hydroxy-terminated curativesmay be added to the aforementioned polyurethane composition. Suitablediol, triol, and tetraol groups include ethylene glycol; diethyleneglycol; polyethylene glycol; propylene glycol; polypropylene glycol;lower molecular weight polytetramethylene ether glycol;1,3-bis(2-hydroxyethoxy) benzene;1,3-bis-[2-(2-hydroxyethoxy)ethoxy]benzene;1,3-bis-{2-[2-(2-hydroxyethoxy)ethoxy]ethoxy} benzene; 1,4-butanediol;1,5-pentanediol; 1,6-hexanediol; resorcinol-di-(β-hydroxyethyl)ether;hydroquinone-di-(β-hydroxyethyl)ether; and mixtures thereof. Preferredhydroxy-terminated curatives include 1,3-bis(2-hydroxyethoxy)benzene;1,3-bis-[2-(2-hydroxyethoxy) ethoxy]benzene;1,3-bis-{2-[2-(2-hydroxyethoxy)ethoxy]ethoxy} benzene; 1,4-butanediol,and mixtures thereof. Preferably, the hydroxy-terminated curatives havemolecular weights ranging from about 48 to 2000. It should be understoodthat molecular weight, as used herein, is the absolute weight averagemolecular weight and would be understood as such by one of ordinaryskill in the art.

Both the hydroxy-terminated and amine curatives can include one or moresaturated, unsaturated, aromatic, and cyclic groups. Additionally, thehydroxy-terminated and amine curatives can include one or more halogengroups. The polyurethane composition can be formed with a blend ormixture of curing agents. If desired, however, the polyurethanecomposition may be formed with a single curing agent.

In a preferred embodiment of the present invention, saturatedpolyurethanes are used to form one or more of the cover layers,preferably the outer cover layer, and may be selected from among bothcastable thermoset and thermoplastic polyurethanes

Thermosetting polyurethanes or polyureas are suitable for the outercover layers of the golf balls of the invention.

Additionally, polyurethane can be replaced with or blended with apolyurea material. Polyureas are distinctly different from polyurethanecompositions, giving better shear resistance. The polyurea-basedcompositions are preferably saturated in nature.

The polyether amine may be blended with additional polyols to formulatecopolymers that are reacted with excess isocyanate to form the polyureaprepolymer. In one embodiment, less than about 30 percent polyol byweight of the copolymer is blended with the saturated polyether amine.In another embodiment, less than about 20 percent polyol by weight ofthe copolymer, preferably less than about 15 percent by weight of thecopolymer, is blended with the polyether amine The polyols listed abovewith respect to the polyurethane prepolymer, e.g., polyether polyols,polycaprolactone polyols, polyester polyols, polycarbonate polyols,hydrocarbon polyols, other polyols, and mixtures thereof, are alsosuitable for blending with the polyether amine. The molecular weight ofthese polymers may be from about 200 to about 4000, but also may be fromabout 1000 to about 3000, and more preferably are from about 1500 toabout 2500.

The polyurea composition can be formed by crosslinking a polyureaprepolymer with a single curing agent or a blend of curing agents. Thecuring agent of the invention is preferably an amine-terminated curingagent, more preferably a secondary diamine curing agent so that thecomposition contains only urea linkages. In one embodiment, theamine-terminated curing agent may have a molecular weight of about 64 orgreater. In another embodiment, the molecular weight of the amine-curingagent is about 2000 or less. As discussed above, certainamine-terminated curing agents may be modified with a compatibleamine-terminated freezing point depressing agent or mixture ofcompatible freezing point depressing agents

Suitable amine-terminated curing agents include, but are not limited to,ethylene diamine; hexamethylene diamine; 1-methyl-2,6-cyclohexyldiamine; tetrahydroxypropylene ethylene diamine; 2,2,4- and2,4,4-trimethyl-1,6-hexanediamine;4,4′-bis-(sec-butylamino)-dicyclohexylmethane;1,4-bis-(sec-butylamino)-cyclohexane;1,2-bis-(sec-butylamino)-cyclohexane; derivatives of4,4′-bis-(sec-butylamino)-dicyclohexylmethane; 4,4′-dicyclohexylmethanediamine; 1,4-cyclohexane-bis-(methylamine);1,3-cyclohexane-bis-(methylamine); diethylene glycoldi-(aminopropyl)ether; 2-methylpentamethylene-diamine;diaminocyclohexane; diethylene triamine; triethylene tetramine;tetraethylene pentamine; propylene diamine; 1,3-diaminopropane;dimethylamino propylamine; diethylamino propylamine; dipropylenetriamine; imido-bis-propylamine; monoethanolamine, diethanolamine;3,5-diethyltoluene-2,4-diamine; triethanolamine; monoisopropanolamine,diisopropanolamine; isophoronediamine;4,4′-methylenebis-(2-chloroaniline);3,5-dimethylthio-2,4-toluenediamine;3,5-dimethylthio-2,6-toluenediamine; 3,5-diethylthio-2,4-toluenediamine;3,5-diethylthio-2,6-toluenediamine;4,4′-bis-(sec-butylamino)-diphenylmethane and derivatives thereof;1,4-bis-(sec-butylamino)-benzene; 1,2-bis-(sec-butylamino)-benzene;N,N′-dialkylamino-diphenylmethane;N,N,N′,N′-tetrakis(2-hydroxypropyl)ethylene diamine;trimethyleneglycol-di-p-aminobenzoate;polytetramethyleneoxide-di-p-aminobenzoate;4,4′-methylenebis-(3-chloro-2,6-diethyleneaniline);4,4′-methylenebis-(2,6-diethylaniline); meta-phenylenediamine;paraphenylenediamine; and mixtures thereof. In one embodiment, theamine-terminated curing agent is4,4′-bis-(sec-butylamino)-dicyclohexylmethane.

Suitable saturated amine-terminated curing agents include, but are notlimited to, ethylene diamine; hexamethylene diamine;1-methyl-2,6-cyclohexyl diamine; tetrahydroxypropylene ethylene diamine;2,2,4- and 2,4,4-trimethyl-1,6-hexanediamine;4,4′-bis-(sec-butylamino)-dicyclohexylmethane;1,4-bis-(sec-butylamino)-cyclohexane;1,2-bis-(sec-butylamino)-cyclohexane; derivatives of4,4′-bis-(sec-butylamino)-dicyclohexylmethane;; 4,4′-dicyclohexylmethanediamine; 4,4′-methylenebis-(2,6-diethylaminocyclohexane;1,4-cyclohexane-bis-(methylamine); 1,3-cyclohexane-bis-(methylamine);diethylene glycol di-(aminopropyl)ether; 2-methylpentamethylene-diamine;diaminocyclohexane; diethylene triamine; triethylene tetramine;tetraethylene pentamine; propylene diamine; 1,3-diaminopropane;dimethylamino propylamine; diethylamino propylamine;imido-bis-propylamine; monoethanolamine, diethanolamine;triethanolamine; monoisopropanolamine, diisopropanolamine;isophoronediamine; triisopropanolamine; and mixtures thereof. Inaddition, any of the polyether amines listed above may be used as curingagents to react with the polyurea prepolymers.

Alternatively, other suitable polymers include partially or fullyneutralized ionomer, metallocene, or other single-site catalyzedpolymer, polyester, polyamide, non-ionomeric thermoplastic elastomer,copolyether-esters, copolyether-amides, polycarbonate, polybutadiene,polyisoprene, polystryrene block copolymers (such asstyrene-butadiene-styrene), styrene-ethylene-propylene-styrene,styrene-ethylene-butylene-styrene, and the like, and blends thereof.

Cover layers of the inventive golf ball may also be formed fromionomeric polymers, preferably highly-neutralized ionomers (HNP). In apreferred embodiment, at least one intermediate layer of the golf ballis formed from an HNP material or a blend of HNP materials. The acidmoieties of the HNP's, typically ethylene-based ionomers, are preferablyneutralized greater than about 70%, more preferably greater than about90%, and most preferably at least about 100%. The HNP's can be also beblended with a second polymer component, which, if containing an acidgroup, may be neutralized in a conventional manner, by the organic fattyacids of the present invention, or both. The second polymer component,which may be partially or fully neutralized, preferably comprisesionomeric copolymers and terpolymers, ionomer precursors,thermoplastics, polyamides, polycarbonates, polyesters, polyurethanes,polyureas, thermoplastic elastomers, polybutadiene rubber, balata,metallocene-catalyzed polymers (grafted and non-grafted), single-sitepolymers, high-crystalline acid polymers, cationic ionomers, and thelike. HNP polymers typically have a material hardness of between about20 and about 80 Shore D, and a flexural modulus of between about 3,000psi and about 200,000 psi.

In one embodiment of the present invention the HNP's are ionomers and/ortheir acid precursors that are preferably neutralized, either fully orpartially, with organic acid copolymers or the salts thereof. The acidcopolymers are preferably α-olefin, such as ethylene, C₃₋₈α,β-ethylenically unsaturated carboxylic acid, such as acrylic andmethacrylic acid, copolymers. They may optionally contain a softeningmonomer, such as alkyl acrylate and alkyl methacrylate, wherein thealkyl groups have from 1 to 8 carbon atoms.

The acid copolymers can be described as E/X/Y copolymers where E isethylene, X is an α,β-ethylenically unsaturated carboxylic acid, and Yis a softening comonomer. In a preferred embodiment, X is acrylic ormethacrylic acid and Y is a C₁₋₈ alkyl acrylate or methacrylate ester. Xis preferably present in an amount from about 1 to about 35 weightpercent of the polymer, more preferably from about 5 to about 30 weightpercent of the polymer, and most preferably from about 10 to about 20weight percent of the polymer. Y is preferably present in an amount fromabout 0 to about 50 weight percent of the polymer, more preferably fromabout 5 to about 25 weight percent of the polymer, and most preferablyfrom about 10 to about 20 weight percent of the polymer.

Specific acid-containing ethylene copolymers include, but are notlimited to, ethylene/acrylic acid/n-butyl acrylate, ethylene/methacrylicacid/n-butyl acrylate, ethylene/methacrylic acid/iso-butyl acrylate,ethylene/acrylic acid/iso-butyl acrylate, ethylene/methacrylicacid/n-butyl methacrylate, ethylene/acrylic acid/methyl methacrylate,ethylene/acrylic acid/methyl acrylate, ethylene/methacrylic acid/methylacrylate, ethylene/methacrylic acid/methyl methacrylate, andethylene/acrylic acid/n-butyl methacrylate. Preferred acid-containingethylene copolymers include, ethylene/methacrylic acid/n-butyl acrylate,ethylene/acrylic acid/n-butyl acrylate, ethylene/methacrylic acid/methylacrylate, ethylene/acrylic acid/ethyl acrylate, ethylene/methacrylicacid/ethyl acrylate, and ethylene/acrylic acid/methyl acrylatecopolymers. The most preferred acid-containing ethylene copolymers are,ethylene/(meth) acrylic acid/n-butyl, acrylate, ethylene/(meth)acrylicacid/ethyl acrylate, and ethylene/(meth) acrylic acid/methyl acrylatecopolymers.

Ionomers are typically neutralized with a metal cation, such as Li, Na,Mg, K, Ca, or Zn. It has been found that by adding sufficient organicacid or salt of organic acid, along with a suitable base, to the acidcopolymer or ionomer, the ionomer can be neutralized, without losingprocessability, to a level much greater than for a metal cation.Preferably, the acid moieties are neutralized greater than about 80%,preferably from 90-100%, most preferably 100% without losingprocessability. This is accomplished by melt-blending an ethyleneα,β-ethylenically unsaturated carboxylic acid copolymer, for example,with an organic acid or a salt of organic acid, and adding a sufficientamount of a cation source to increase the level of neutralization of allthe acid moieties (including those in the acid copolymer and in theorganic acid) to greater than 90%, (preferably greater than 100%).

The organic acids of the present invention are aliphatic, mono- ormulti-functional (saturated, unsaturated, or multi-unsaturated) organicacids. Salts of these organic acids may also be employed. The salts oforganic acids of the present invention include the salts of barium,lithium, sodium, zinc, bismuth, chromium, cobalt, copper, potassium,strontium, titanium, tungsten, magnesium, cesium, iron, nickel, silver,aluminum, tin, or calcium, salts of fatty acids, particularly stearic,behenic, erucic, oleic, linoelic or dimerized derivatives thereof. It ispreferred that the organic acids and salts of the present invention berelatively non-migratory (they do not bloom to the surface of thepolymer under ambient temperatures) and non-volatile (they do notvolatilize at temperatures required for melt-blending).

The ionomers of the invention may also be more conventional ionomers,i.e., partially-neutralized with metal cations. The acid moiety in theacid copolymer is neutralized about 1 to about 90%, preferably at leastabout 20 to about 75%, and more preferably at least about 40 to about70%, to form an ionomer, by a cation such as lithium, sodium, potassium,magnesium, calcium, barium, lead, tin, zinc, aluminum, or a mixturethereof.

A moisture vapor barrier layer, such as disclosed in U.S. Pat. Nos.6,632,147; 6,932,720; 7,004,854; and 7,182,702, all of which areincorporated by reference herein in their entirety, are optionallyemployed between the cover layer and the core. The moisture barrierlayer may be disposed between the outer core layer and the cover layer.The moisture vapor barrier protects the inner and outer cores fromdegradation due to exposure to moisture and extends the usable life ofthe golf ball. In one embodiment, the moisture barrier layer comprises aLCBNCP as defined and described herein. The moisture vapor transmissionrate of the moisture barrier layer is selected to be less than themoisture vapor transmission rate of the cover layer. The moisturebarrier layer has a specific gravity of from about 1.1 to about 1.2 anda thickness of less than about 0.03 inches. Other suitable materials forthe moisture barrier layer include a combination of a styrene blockcopolymer and a flaked metal, for example aluminum flake.

The LCBNCP constituting the layer(s) of the inventive golf ball maycontain additives, ingredients, and other materials in amounts that donot detract from the properties of the final composition. These additivematerials include, but are not limited to, activators such as calcium ormagnesium oxide; fatty acids such as stearic acid and salts thereof;fillers and reinforcing agents such as organic or inorganic particles,for example, clays, talc, calcium, magnesium carbonate, silica, aluminumsilicates, zeolites, powdered metals, and organic or inorganic fibers,plasticizers such as dialkyl esters of dicarboxylic acids; surfactants;softeners; tackifiers; waxes; ultraviolet (UV) light absorbers andstabilizers; antioxidants; optical brighteners; whitening agents such astitanium dioxide and zinc oxide; dyes and pigments; processing aids;release agents; and wetting agents. These compositions provide improvedmelt processability, and a balance of ball performance.

Blowing/foaming agents may also be particularly compatible with theLCBNCP incorporated golf ball of the invention, including, for examplethose disclosed in U.S. Pat. No. 7,708,654. Typical physicalfoaming/blowing agents include volatile liquids such as freons (CFCs),other halogenated hydrocarbons, water, aliphatic hydrocarbons, gases,and solid blowing agents, i.e., compounds that liberate gas as a resultof desorption of gas. Preferably, the blowing agent includes anadsorbent. Typical adsorbents include, for example, activated carbon,calcium carbonate, diatomaceous earth, and silicates saturated withcarbon dioxide.

Chemical foaming/blowing agents are more preferred, particularly whenthe core includes thermoplastics such as ionomers, highly neutralizedpolymers, and polyolefins. Chemical blowing agents may be inorganic,such as ammonium carbonate and carbonates of alkalai metals, or may beorganic, such as azo and diazo compounds, such as nitrogen-based azocompounds. Suitable azo compounds include, but are not limited to,2,2′-azobis(2-cyanobutane), 2,2′-azobis(methylbutyronitrile),azodicarbonamide, p,p′-oxybis(benzene sulfonyl hydrazide), p-toluenesulfonyl semicarbazide, p-toluene sulfonyl hydrazide. Other blowingagents include any of the Celogens® sold by Crompton ChemicalCorporation, and nitroso compounds, sulfonylhydrazides, azides oforganic acids and their analogs, triazines, tri- and tetrazolederivatives, sulfonyl semicarbazides, urea derivatives, guanidinederivatives, and esters such as alkoxyboroxines. Other possible blowingagents include agents that liberate gasses as a result of chemicalinteraction between components such as mixtures of acids and metals,mixtures of organic acids and inorganic carbonates, mixtures of nitrilesand ammonium salts, and the hydrolytic decomposition of urea.

Alternatively, low specific gravity can be achieved by incorporating lowdensity fillers or agents such as hollow fillers or microspheres in thepolymeric matrix, where the cured composition has the preferred specificgravity. Moreover, the polymeric matrix can be foamed to decrease itsspecific gravity, microballoons, or other low density fillers asdescribed in U.S. Pat. No. 6,692,380 (“'380 patent”). The '380 patent isincorporated by reference in its entirety.

The LCBNCP in the golf ball of this invention may be blended withnon-ionomeric and olefin-based ionomeric polymers to form thecomposition that will be used to make the golf ball layer. Examples ofnon-ionomeric polymers include vinyl resins, polyolefins including thoseproduced using a single-site catalyst or a metallocene catalyst,polyurethanes, polyureas, polyamides, polyphenylenes, polycarbonates,polyesters, polyacrylates, engineering thermoplastics, and the like.Also, in one embodiment of the invention, processability of the golfball of the invention may even be enhanced by incorporating in the corea metallocene-catalyzed polybutadiene.

Olefin-based ionomers, such as ethylene-based copolymers, normallyinclude an unsaturated carboxylic acid, such as methacrylic acid,acrylic acid, or maleic acid. Other possible carboxylic acid groupsinclude, for example, crotonic, maleic, fumaric, and itaconic acid. “Lowacid” and “high acid” olefin-based ionomers, as well as blends of suchionomers, may be used. In general, low acid ionomers are considered tobe those containing 16 wt. % or less of carboxylic acid, whereas highacid ionomers are considered to be those containing greater than 16 wt.% of carboxylic acid. The acidic group in the olefin-based ioniccopolymer is partially or totally neutralized with metal ions such aszinc, sodium, lithium, magnesium, potassium, calcium, manganese, nickel,chromium, copper, or a combination thereof. For example, ionomericresins having carboxylic acid groups that are neutralized from about 10percent to about 100 percent may be used. In one embodiment, the acidgroups are partially neutralized. That is, the neutralization level isfrom 10 to 80%, more preferably 20 to 70%, and most preferably 30 to50%. In another embodiment, the acid groups are highly or fullyneutralized. Or, the neutralization level may be from about 80 to 100%,more preferably 90 to 100%, and most preferably 95 to 100%. The blendmay contain about 5 to about 30% by weight of the LCBNCP and about 95 toabout 70% by weight of a partially, highly, or fully-neutralizedolefin-based ionomeric copolymer. The above-mentioned blends may containone or more suitable compatibilizers such as glycidyl acrylate orglycidyl methacrylate or maleic anhydride containing-polymers.

The core may contain sections having the same hardness or differenthardness levels. That is, there can be uniform hardness throughout thedifferent sections of the core or there can be hardness gradients acrossthe layers. For example, in single cores, there may be a hard-to-softgradient (a “positive” gradient) from the surface of the core to thegeometric center of the core. In other instances, there may be asoft-to-hard gradient (a “negative” gradient) or zero hardness gradientfrom the core's surface to the core's center. For dual core golf balls,the inner core layer may have a surface hardness that is less than thegeometric center hardness to define a first “negative” gradient. Asdiscussed above, an outer core layer may be formed around the inner corelayer, and the outer core layer may have an outer surface hardness lessthan its inner surface hardness to define a second “negative” gradient.In other versions, the hardness gradients from surface to center may behard-to-soft (“positive”), or soft-to-hard (“negative”), or acombination of both gradients. In still other versions the hardnessgradients from surface to center may be “zero” (that is, the hardnessvalues are substantially the same.) Methods for making cores havingpositive, negative, and zero hardness gradients are known in the art asdescribed in, for example, U.S. Pat. Nos. 7,537,530; 7,537,529;7,427,242; and 7,410,429, the disclosures of which are herebyincorporated by reference.

A golf ball according to the invention may therefore incorporate theLCBNCP in a core to achieve various hardness gradients therein. Forexample, the LCBNCP may be incorporated in a single-core constituting asolid core having a “positive” hardness gradient (that is, the outersurface of the core is harder than its geometric center.) In a secondembodiment, the LCBNCP may be incorporated in a dual-core comprising aninner core and a surrounding outer core layer. The inner core has a“positive” hardness gradient and the outer core layer has a “negative”hardness gradient (that is, the outer surface of the outer core layer issofter than the inner surface of the outer core layer.) Otherembodiments of golf balls having various combinations of positive,negative, and zero hardness gradients may be made in accordance withthis invention. For example, the inner core may have a positive hardnessgradient and the outer core layer also may have a positive hardnessgradient. In another example, the inner core may have a positivehardness gradient and the outer core layer may have a “zero” hardnessgradient. (That is, the hardness values of the outer surface of theouter core layer and the inner surface of the outer core layer aresubstantially the same.) Particularly, the term, “zero hardnessgradient” as used herein, means a surface to center Shore C hardnessgradient of less than 8, preferably less than 5 and most preferably lessthan 3 and may have a value of zero or negative 1 to negative 25. Theterm, “negative hardness gradient” as used herein, means a surface tocenter Shore C hardness gradient of less than zero. The terms, zerohardness gradient and negative hardness gradient, may be used hereininterchangeably to refer to hardness gradients of negative 1 to negative25. The term, “positive hardness gradient” as used herein, means asurface to center Shore C hardness gradient of 8 or greater, preferably10 or greater, and most preferably 20 or greater. By the term, “steeppositive hardness gradient” as used herein, it is meant surface tocenter Shore C hardness gradient of 20 or greater, more preferably 25 orgreater, and most preferably 30 or greater. For example, the LCBNCPcontaining core may have a step positive hardness gradient of 35, 40, or45 Shore C or greater. Methods for measuring the hardness of the innercore and surrounding layers and determining the hardness gradients arediscussed in further detail below.

The center hardness of a core is obtained according to the followingprocedure. The core is gently pressed into a hemispherical holder havingan internal diameter approximately slightly smaller than the diameter ofthe core, such that the core is held in place in the hemisphericalportion of the holder while concurrently leaving the geometric centralplane of the core exposed. The core is secured in the holder byfriction, such that it will not move during the cutting and grindingsteps, but the friction is not so excessive that distortion of thenatural shape of the core would result. The core is secured such thatthe parting line of the core is roughly parallel to the top of theholder. The diameter of the core is measured 90 degrees to thisorientation prior to securing. A measurement is also made from thebottom of the holder to the top of the core to provide a reference pointfor future calculations. A rough cut is made slightly above the exposedgeometric center of the core using a band saw or other appropriatecutting tool, making sure that the core does not move in the holderduring this step. The remainder of the core, still in the holder, issecured to the base plate of a surface grinding machine. The exposed‘rough’ surface is ground to a smooth, flat surface, revealing thegeometric center of the core, which can be verified by measuring theheight from the bottom of the holder to the exposed surface of the core,making sure that exactly half of the original height of the core, asmeasured above, has been removed to within 0.004 inches. Leaving thecore in the holder, the center of the core is found with a center squareand carefully marked and the hardness is measured at the center markaccording to ASTM D-2240. Additional hardness measurements at anydistance from the center of the core can then be made by drawing a lineradially outward from the center mark, and

measuring the hardness at any given distance along the line, typicallyin 2 mm increments from the center. The hardness at a particulardistance from the center should be measured along at least two,preferably four, radial arms located 180° apart, or 90° apart,respectively, and then averaged. All hardness measurements performed ona plane passing through the geometric center are performed while thecore is still in the holder and without having disturbed itsorientation, such that the test surface is constantly parallel to thebottom of the holder, and thus also parallel to the properly alignedfoot of the durometer.

The outer surface hardness of a golf ball layer is measured on theactual outer surface of the layer and is obtained from the average of anumber of measurements taken from opposing hemispheres, taking care toavoid making measurements on the parting line of the core or on surfacedefects, such as holes or protrusions. Hardness measurements are madepursuant to ASTM D-2240 “Indentation Hardness of Rubber and Plastic byMeans of a Durometer.” Because of the curved surface, care must be takento ensure that the golf ball or golf ball subassembly is centered underthe durometer indentor before a surface hardness reading is obtained. Acalibrated, digital durometer, capable of reading to 0.1 hardness unitsis used for the hardness measurements. The digital durometer must beattached to, and its foot made parallel to, the base of an automaticstand. The weight on the durometer and attack rate conform to ASTMD-2240. In certain embodiments, a point or plurality of points measuredalong the “positive” or “negative” gradients may be above or below aline fit through the gradient and its outermost and innermost hardnessvalues. In an alternative preferred embodiment, the hardest point alonga particular steep “positive” or “negative” gradient may be higher thanthe value at the innermost portion of the inner core (the geometriccenter) or outer core layer (the inner surface)—as long as the outermostpoint (i.e., the outer surface of the inner core) is greater than (for“positive”) or lower than (for “negative”) the innermost point (i.e.,the geometric center of the inner core or the inner surface of the outercore layer), such that the “positive” and “negative” gradients remainintact.

As discussed above, the direction of the hardness gradient of a golfball layer is defined by the difference in hardness measurements takenat the outer and inner surfaces of a particular layer. The centerhardness of an inner core and hardness of the outer surface of an innercore in a single-core ball or outer core layer are readily determinedaccording to the test procedures provided above. The outer surface ofthe inner core layer (or other optional intermediate core layers) in adual-core ball are also readily determined according to the proceduresgiven herein for measuring the outer surface hardness of a golf balllayer, if the measurement is made prior to surrounding the layer with anadditional core layer. Once an additional core layer surrounds a layerof interest, the hardness of the inner and outer surfaces of any inneror intermediate layers can be difficult to determine. Therefore, forpurposes of the present invention, when the hardness of the inner orouter surface of a core layer is needed after the inner layer has beensurrounded with another core layer, the test procedure described abovefor measuring a point located 1 mm from an interface is used.

Also, it should be understood that there is a fundamental differencebetween “material hardness” and “hardness as measured directly on a golfball.” For purposes of the present invention, material hardness ismeasured according to ASTM D2240 and generally involves measuring thehardness of a flat “slab” or “button” formed of the material. Surfacehardness as measured directly on a golf ball (or other sphericalsurface) typically results in a different hardness value. The differencein “surface hardness” and “material hardness” values is due to severalfactors including, but not limited to, ball construction (that is, coretype, number of cores and/or cover layers, and the like); ball (orsphere) diameter; and the material composition of adjacent layers. Italso should be understood that the two measurement techniques are notlinearly related and, therefore, one hardness value cannot easily becorrelated to the other. Shore C hardness was measured according to thetest methods D-2240.

Several different methods can be used to measure compression, includingAtti compression, Riehle compression, load/deflection measurements at avariety of fixed loads and offsets, and effective modulus. See, e.g.,Compression by Any Other Name, Science and Golf IV, Proceedings of theWorld Scientific Congress of Golf (Eric Thain ed., Routledge, 2002) (“J.Dalton”) The term compression, as used herein, refers to Atti or PGAcompression and is measured using an Atti compression test device. Apiston compresses a ball against a spring and the piston remains fixedwhile deflection of the spring is measured at 1.25 mm (0.05 inches).Where a core has a very low stiffness, the compression measurement willbe zero at 1.25 mm. In order to measure the compression of a core usingan Atti compression tester, the core must be shimmed to a diameter of1.680 inches because these testers are designed to measure objectshaving that diameter. Atti compression units can be converted to Riehle(cores), Riehle (balls), 100 kg deflection, 130-10 kg deflection oreffective modulus using the formulas set forth in J. Dalton. Theapproximate relationship that exists between Atti or PGA compression andRiehle compression can be expressed as: (Atti or PGAcompression)=(160−Riehle Compression). Thus, a Riehle compression of 100would be the same as an Atti compression of 60.

COR, as used herein, is determined by firing a golf ball or golf ballsubassembly (e.g., a golf ball core) from an air cannon at two givenvelocities and calculating the COR at a velocity of 125 ft/s. Ballvelocity is calculated as a ball approaches ballistic light screenswhich are located between the air cannon and a steel plate at a fixeddistance. As the ball travels toward the steel plate, each light screenis activated, and the time at each light screen is measured. Thisprovides an incoming transit time period inversely proportional to theball's incoming velocity. The ball impacts the steel plate and reboundsthrough the light screens, which again measure the time period requiredto transit between the light screens. This provides an outgoing transittime period inversely proportional to the ball's outgoing velocity. CORis then calculated as the ratio of the outgoing transit time period tothe incoming transit time period, COR=V_(out)/V_(in)=T_(in)/T_(out).Preferably, a golf ball according to the present invention has a COR ofat least about 0.78, more preferably, at least about 0.80.

The spin rate of a golf ball also remains an important golf ballcharacteristic. High spin rate allows skilled players more flexibilityin stopping the ball on the green if they are able to control a highspin ball. On the other hand, recreational players often prefer a lowspin ball since they do not have the ability to intentionally controlthe ball, and lower spin balls tend to drift less off the green.

Golf ball spin is dependent on variables including, for example,distribution of the density or specific gravity within a golf ball. Forexample, when the center has a higher density or specific gravity thanthe outer layers, a lower moment of inertia results which increases spinrate. Alternatively, when the density or specific gravity isconcentrated in the outer regions of the golf ball, a higher moment ofinertia results with a lower spin rate. The moment of inertia for a onepiece ball that is 1.62 ounces and 1.68 inches in diameter isapproximately 0.4572 oz-in², which is the baseline moment of inertiavalue.

Accordingly, by varying the materials and the hardness of the regions ofeach core layer, different moments of inertia may be achieved for thegolf ball of the present invention. In one embodiment, the resultinggolf ball has a moment of inertia of from about to 0.440 to about 0.455oz-in². In another embodiment, the golf balls of the present inventionhave a moment of inertia of from about 0.456 oz-in² to about 0.470oz-in². In yet another embodiment, the golf ball has a moment of inertiaof from about 0.450 oz-in² to about 0.460 oz-in².

In one embodiment, the LCBNCP composition of the golf ball of thepresent invention has a moisture vapor transmission rate (“MVTR”) of 10g/m²/day or less, preferably 8 or less, more preferably 2 or less. Asused herein, MVTR is given in g/m²/day, and is measured at 20° C.,according to ASTM F1249-99.

By way of non-limiting prophetic example, the novelty of the inventionmay be demonstrated as follows. Table I below reveals the superiorprocessability of four core material formulations for incorporation inthe inventive golf ball over three comparative core materialformulations under the same conditions. All of the core materials wouldbe formulated to be incorporated in a golf ball having high COR and abroad range of compressions as arranged in Table I. In table I, each ofthe core materials for incorporation in an inventive golf ball wouldinclude a polybutadiene composition incorporating 15 wt % of along-chain branched neodymium-catalyzed polybutadiene. The solutionviscosities of the long-chain branched neodymium-catalyzedpolybutadienes in each of the inventive golf ball core materials wouldbe less than 165 mPa·s as indicated in Table I. Meanwhile, each of thecomparative golf ball core materials would have the same formulation asthat of the inventive golf ball core material except that the long-chainbranched neodymium-catalyzed polybutadiene of the inventive golf ballcore material would be replaced with a neodymium-catalyzed polybutadienehaving a solution viscosity of 165 mPa·s or greater. Specifically,Ex1-Ex4 might be LCBNCP's having SV's of 145 (LANXESS BUNA CB 25), 130,100, and 85, respectively. The comparative examples 1, 2 and 3 wouldincorporate the following neodymium-catalyzed polybutadienes,respectively: LANXESS BUNA CB 22 (SV 400); LANXESS BUNA CB 23 (SV 300);and LANXESS BUNA CB 24 (SV 165).

The processability of each golf ball core composition/material would beevaluated. In particular, for each of the four inventive golf ball coreformulations as well as the three comparative golf ball coreformulations, the following would be measured: quality of mix,extrudability, appearance (surface smoothness of extrudate), cold flow,green strength, tack, and backrinding.

Quality of mix, extrudability, surface smoothness, tack, and backrindingmay be observed visually for each material prior to molding or by anyother method known in the art. Cold flow may be examined by thefollowing method or any other method known in the art. Eachneodymium-catalyzed raw polybutadiene or compounded golf ball corestock, having the dimensions 120 mm (length) by 115 mm (width) and 100mm (depth) would be placed/fit into one end of a steel box having thedimensions 120 mm length by 200 mm width and 100 mm depth. A 6 kg steelblock is placed and fit on top of the slug having dimensions 120 mm by115 mm width and X mm depth. The change (increase) in the slug's widthis monitored/marked on the box at discrete intervals over 10,000minutes. Green strength may be evaluated using any method known in theart for testing the tensile strength and/or tensile modulus of theuncured rubber.

In Table I, the core materials of an inventive golf ball having atargeted overall golf ball (“GB”) COR of 0.788 and a variety ofcompressions are assigned a rating of “great” since each of these corematerials displays excellent processability in the 7 processingcategories identified above. The core materials in comparative example 3are assigned a rating of “worse” because their processability isinferior to that of each of the inventive cores under the sameconditions. In turn, the core materials in comparative example 2 areassigned a rating of “even worse” because these comparative coresdisplay even worse processability at a given condition than the corematerials of comparative example 2. Finally, the core materials ofcomparative example 1 are assigned a rating of “worst” since these corematerials display the worst processability of any of the other corematerials under the same conditions.

And this assessment could be repeated for different weight % contents ofLCBNCP in the inventive golf ball core materials, intermediate layermaterials and/or cover materials, such as 50 wt % or 90 wt %, forexample.

Accordingly, an inventive golf ball including a polybutadienecomposition incorporating 15 wt % or even 50 wt % or even 90 wt % of along-chain branched neodymium-catalyzed polybutadiene having a solutionviscosity less than 165 mPa·s would possess and display superiorprocessability over the comparative golf balls includingneodymium-catalyzed polybutadienes having solution viscosities of 165mPa·s or greater.

TABLE I Processability of Golf Ball Materials* including PolybutadieneComposition incorporating 15 wt % of LCBNCP having Solution viscosity ofless than 165 mPa · s Processability of GB core material at targeted GBCOR & Comp. Comp. Comp. compression Ex. 1 Ex. 2 Ex. 3 Ex 1 Ex 2 Ex 3 Ex4 0.788 & 25 Worst Even Worse Worse Great Great Great Great 0.791 & 35Worst Even Worse Worse Great Great Great Great 0.794 & 45 Worst EvenWorse Worse Great Great Great Great 0.797 & 55 Worst Even Worse WorseGreat Great Great Great 0.800 & 65 Worst Even Worse Worse Great GreatGreat Great 0.803 & 75 Worst Even Worse Worse Great Great Great Great0.806 & 85 Worst Even Worse Worse Great Great Great Great 0.809 & 95Worst Even Worse Worse Great Great Great Great 0.812 & 105 Worst EvenWorse Worse Great Great Great Great 0.815 & 115 Worst Even Worse WorseGreat Great Great Great *In Table I, the balance of golf ball componentsmay include, for example, a “masterbatch” composition comprising one ofthe following: (1) Where the golf ball material is a core formulationcomprising the polybutadiene composition incorporating LCBNCP, themasterbatch composition may comprise, for example, 100 phr polybutadienerubber, 0.6 phr of Perkadox BC-FF peroxide initiator, 20-40 phr ofSR-526 Zinc diacrylate coagent (amount varies according to desiredcompression), 5 phr of ZnO filler and BaSO4 density adjusting filler(amount varies according to desired specific gravity); (2) Where thegolf ball material is an inner cover or intermediate layer formulationcomprising the polybutadiene composition incorporating LCBNCP, themasterbatch composition may comprise, for example, 100 phr of Surlyn9910; and (3) Where the golf ball material is an outer cover formulationcomprising the polybutadiene composition incorporating LCBNCP, themasterbatch composition may comprise, for example, 100 phr of Estane58881 (TPU).

Accordingly, a golf ball according to the invention comprising in atleast one of its core, intermediate layer, inner cover layer or outercover layer an LCBNCP as described herein improves golf ballprocessability/processing characteristics including, for exampleexcellent quality of mix, extrudability, extrudate surface smoothness,controlled cold flow, greater green strength, suitable tack, lessbackrinding, and improved compatability with other golf ball materialsincluding for example foaming agents.

The LCBNCP's disclosed in the examples of Table I above represent onlyseveral of many possible formulations for the LCBNCP which may bemodified or replaced with any formulation consistent with the disclosureherein, including combinations and blends of several LCBNCP's or atleast one LCBNCP with at least one linear neodymium-catalyzedpolybutadiene.

Unless otherwise expressly specified, all of the numerical ranges,amounts, values and percentages such as those for amounts of materials,and others in the specification may be read as if prefaced by the word“about” even though the term “about” may not expressly appear with thevalue, amount or range. Accordingly, unless indicated to the contrary,the numerical parameters set forth in the specification and attachedclaims are approximations that may vary depending upon the desiredproperties sought to be obtained by the present invention. At the veryleast, and not as an attempt to limit the application of the doctrine ofequivalents to the scope of the claims, each numerical parameter shouldat least be construed in light of the number of reported significantdigits and by applying ordinary rounding techniques.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contains certainerrors necessarily resulting from the standard deviation found in theirrespective testing measurements. Furthermore, when numerical ranges ofvarying scope are set forth herein, it is contemplated that anycombination of these values inclusive of the recited values may be used.

While it is apparent that the illustrative embodiments of the inventiondisclosed herein fulfill the preferred embodiments of the presentinvention, it is appreciated that numerous modifications and otherembodiments may be devised by those skilled in the art. Examples of suchmodifications include reasonable variations of the numerical valuesand/or materials and/or components discussed above. Hence, the numericalvalues stated above and claimed below specifically include those valuesand the values that are approximate to those stated and claimed values.Therefore, it will be understood that the appended claims are intendedto cover all such modifications and embodiments, which would come withinthe spirit and scope of the present invention.

The invention described and claimed herein is not to be limited in scopeby the specific embodiments herein disclosed, since these embodimentsare intended as illustrations of several aspects of the invention. Anyequivalent embodiments are intended to be within the scope of thisinvention. Indeed, various modifications of the invention in addition tothose shown and described herein will become apparent to those skilledin the art from the foregoing description. For example, the compositionsof the present invention may be used in a variety of equipment. Suchmodifications are also intended to fall within the scope of the appendedclaims.

While any of the embodiments herein may have any known dimple number andpattern, a preferred number of dimples is 252 to 456, and morepreferably is 330 to 392. The dimples may comprise any width, depth, andedge angle disclosed in the prior art and the patterns may comprisesmultitudes of dimples having different widths, depths and edge angles.The parting line configuration of said pattern may be either a straightline or a staggered wave parting line (SWPL). Most preferably the dimplenumber is 330, 332, or 392 and comprises 5 to 7 dimples sizes and theparting line is a SWPL.

In any of these embodiments the single-layer core may be replaced with atwo or more layer core wherein at least one core layer has a negativehardness gradient. Other than in the operating examples, or unlessotherwise expressly specified, all of the numerical ranges, amounts,values and percentages such as those for amounts of materials and othersin the specification may be read as if prefaced by the word “about” eventhough the term “about” may not expressly appear with the value, amountor range.

Accordingly, unless indicated to the contrary, the numerical parametersset forth in the specification and attached claims are approximationsthat may vary depending upon the desired properties sought to beobtained by the present invention. At the very least, and not as anattempt to limit the application of the doctrine of equivalents to thescope of the claims, each numerical parameter should at least beconstrued in light of the number of reported significant digits and byapplying ordinary rounding techniques.

1. A golf ball comprising a long-chain branched neodymium-catalyzedpolybutadiene having a cis-1,4 content of at least about 96% and asolution viscosity of less than 165 mPa·s, wherein the overall golf ballcomprises a COR of at least about 0.780 and an Atti compression of fromabout 25 to about
 120. 2. The golf ball of claim 1, comprising thelong-chain branched neodymium-catalyzed polybutadiene in an amount of atleast about 5 wt %.
 3. The golf ball of claim 1, comprising thelong-chain branched neodymium-catalyzed polybutadiene in an amount of atleast about 10 wt %.
 4. The golf ball of claim 1, comprising thelong-chain branched neodymium-catalyzed polybutadiene in an amount of atleast about 15 wt %.
 5. The golf ball of claim 1, comprising thelong-chain branched neodymium-catalyzed polybutadiene in an amount offrom about 2 wt % to about 5 wt % or greater.
 6. The golf ball of claim1, wherein the COR is at least about 0.791.
 7. The golf ball of claim 1,wherein the COR is at least about 0.797.
 8. The golf ball of claim 1,wherein the COR is at least about 0.803.
 9. The golf ball of claim 1,wherein the solution viscosity of the long-chain branchedneodymium-catalyzed polybutadiene is less than 155 mPa·s.
 10. The golfball of claim 1, wherein the solution viscosity of the long-chainbranched neodymium-catalyzed polybutadiene is less than 145 mPa·s. 11.The golf ball of claim 1, wherein the solution viscosity of thelong-chain branched neodymium-catalyzed polybutadiene is less than 115mPa·s.
 12. A golf ball comprising: a core, a cover and optionally anintermediate layer disposed between the core and the cover; wherein atleast one of said core, cover and intermediate layer comprises apolybutadiene composition comprising a long-chain branchedneodymium-catalyzed polybutadiene having a cis-1,4 content of at leastabout 96% and a solution viscosity of less than 165 mPa·s.
 13. The golfball of claim 12, the at least one of said core, cover and intermediatelayer comprising the polybutadiene composition in an amount of at leastabout 5 wt %.
 14. The golf ball of claim 12, the polybutadienecomposition comprising the long-chain branched neodymium-catalyzedpolybutadiene in an amount of at least about 5 wt %.
 15. The golf ballof claim 12, wherein the at least one of said core, cover andintermediate layer comprises the polybutadiene composition in an amountof at least about 5 wt % and wherein the polybutadiene compositioncomprises the long-chain branched neodymium-catalyzed polybutadiene inan amount of at least about 5 wt %.
 16. The golf ball of claim 12,wherein the at least one of the core, cover and intermediate layercomprises the polybutadiene composition in an amount of from about 5 wt% to about 95 wt %.
 17. The golf ball of claim 12, wherein the at leastone of the core, cover and intermediate layer comprises thepolybutadiene composition in an amount of from about 10 wt % to about 85wt %.
 18. The golf ball of claim 12, wherein the at least one of thecore, cover and intermediate layer comprises the polybutadienecomposition in an amount of up to about 100 wt %.
 19. The golf ball ofclaim 12, wherein the polybutadiene composition of the at least one ofthe core, intermediate layer and cover comprises the long-chain branchedneodymium-catalyzed polybutadiene in an amount of from about 5 wt % toabout 95 wt %.
 20. The golf ball of claim 12, wherein the polybutadienecomposition of the at least one of the core, intermediate layer andcover comprises the long-chain branched neodymium-catalyzedpolybutadiene in an amount of from about 10 wt % to about 85 wt %. 21.The golf ball of claim 12, wherein the polybutadiene composition of theat least one of the core, intermediate layer and cover comprises thelong-chain branched neodymium-catalyzed polybutadiene in an amount of upto about 100 wt %.
 22. The golf ball of claim 12, wherein the COR is atleast about 0.791.
 23. The golf ball of claim 12, wherein the COR is atleast about 0.797.
 24. The golf ball of claim 12, wherein the COR is atleast about 0.803.
 25. The golf ball of claim 12, wherein the solutionviscosity of the polybutadiene composition is less than 155 mPa·s. 26.The golf ball of claim 12, wherein the solution viscosity of thepolybutadiene composition is less than 145 mPa·s.
 27. The golf ball ofclaim 12, wherein the solution viscosity of the polybutadienecomposition is less than 115 mPa·s.
 28. A golf ball comprising: a core,a cover and optionally an intermediate layer disposed between the coreand the cover; wherein said core comprises a polybutadiene compositioncomprising a long-chain branched neodymium-catalyzed polybutadienehaving a cis-1,4 content of at least about 96% and a solution viscosityof less than 165 mPa·s.
 29. The golf ball of claim 28, said core, coverand intermediate layer comprising the polybutadiene composition in anamount of at least about 5 wt %.
 30. The golf ball of claim 28, thepolybutadiene composition comprising the long-chain branchedneodymium-catalyzed polybutadiene in an amount of at least about 5 wt %.31. The golf ball of claim 28, wherein said core comprises thepolybutadiene composition in an amount of at least about 5 wt % andwherein the polybutadiene composition comprises the long-chain branchedneodymium-catalyzed polybutadiene in an amount of at least about 5 wt %.32. The golf ball of claim 28, wherein the core comprises thepolybutadiene composition in an amount of from about 5 wt % to about 95wt %.
 33. The golf ball of claim 28, wherein the core comprises thepolybutadiene composition in an amount of from about 10 wt % to about 85wt %.
 34. The golf ball of claim 28, wherein the core comprises thepolybutadiene composition in an amount of up to about 100 wt %.
 35. Thegolf ball of claim 28, wherein the polybutadiene composition of the corecomprises the long-chain branched neodymium-catalyzed polybutadiene inan amount of from about 5 wt % to about 95 wt %.
 36. The golf ball ofclaim 28, wherein the polybutadiene composition of the core comprisesthe long-chain branched neodymium-catalyzed polybutadiene in an amountof from about 10 wt % to about 85 wt %.
 37. The golf ball of claim 28,wherein the COR is at least about 0.791.
 38. The golf ball of claim 28,wherein the COR is at least about 0.797.
 39. The golf ball of claim 28,wherein the COR is at least about 0.803.
 40. The golf ball of claim 28,wherein the solution viscosity of the polybutadiene composition is lessthan 155 mPa·s.
 41. The golf ball of claim 28, wherein the solutionviscosity of the polybutadiene composition is less than 145 mPa·s. 42.The golf ball of claim 28, wherein the solution viscosity of thepolybutadiene composition is less than 115 mPa·s.